This invention relates to a disc playback device for playing a disc such as a Compact Disc for the Compact Disc Digital Audio System and an optical type video disc.
Construction of a disc playback device of this type will first be described taking a Compact Disc player for example. A compact Disc player generally automatically transfers a disc inserted in the device to a predetermined playback position in which the disc can be played, feeds an optical pickup head in a radial direction of the disc placed in the playback position and automatically transfers the disc after being played from the playback position to an eject position. For performing these operations, such disc playback device comprises a loading device which performs a loading operation for transferring the disc inserted in the device to the predetermined playback position and an ejecting operation for transferring the disc from the playback position to the eject position and a feed device which performs feeding of the pickup head in the radial direction of the disc.
In the conventional disc playback device, drive motors and drive systems are separately and independently provided for these loading device and the feed device. Each of the loading and feed devices therefore requires not only a drive motor but also a reduction gear train and a drive force transmission system coupled to the drive motor. This is disadvantageous in that it necessitates a complicated construction and a large space in the design of the disc playback device.
It is, therefore, an object of the present invention to provide a disc playback device of a simplified and compact construction employing a single drive motor and drive system used commonly for the loading and feed devices.
As a disc playback device of a type in which a disc is played in a state in which it is housed in a disc case, there is a prior art device which, as disclosed by Japanese Patent Application No. 70478/1984, includes a loading device consisting of a rack provided on the disc case and a pinion provided on the disc playback device and meshing with this rack, the disc case being transferred by rotating the pinion.
In such prior art disc playback device, there arises the problem that if the device is mounted on an automobile, vibration of the automobile is transmitted to the disc case through the rack and pinion in mesh with each other. There is also likelihood that an operator of the device holds the disc case even after the loading operation of the disc case has been started and therefore is delayed in releasing the disc case. If some external force is applied to the disc case for such reason during loading of the case, failure in the loading device will occur due to an excessive force applied to the mechanism for driving the pinion. In a case where distance of transfer is set at a limited value, the transfer operation will be finished before the disc case has reached a desired position with resulting inaccuracy in the loading operation.
It is, therefore, another object of the invention to provide a disc playback device capable of preventing action of an excessive force to the drive system of the loading device and maintaining an accurate loading operation regardless of an external force applied to the device.